[js-testing] more tests for SelectControl (#2877)

* rename spec folder

* remove special handling for viz_type control since it now uses VizTypeControl

* add test for getOptions

* linting

* add test for cwp

* linting

superset/assets/spec/javascripts/explore/components/CheckboxControl_spec.jsx

@@ -0,0 +1,27 @@
+/* eslint-disable no-unused-expressions */
+import React from 'react';
+import { Checkbox } from 'react-bootstrap';
+import sinon from 'sinon';
+import { expect } from 'chai';
+import { describe, it, beforeEach } from 'mocha';
+import { mount } from 'enzyme';
+
+import CheckboxControl from '../../../../javascripts/explore/components/controls/CheckboxControl';
+
+const defaultProps = {
+  name: 'show_legend',
+  onChange: sinon.spy(),
+  value: false,
+};
+
+describe('CheckboxControl', () => {
+  let wrapper;
+
+  beforeEach(() => {
+    wrapper = mount(<CheckboxControl {...defaultProps} />);
+  });
+
+  it('renders a Checkbox', () => {
+    expect(wrapper.find(Checkbox)).to.have.lengthOf(1);
+  });
+});